Beneficiation

Beneficiation is the preparation of mined ore before it is smelted or refined. EPA defines it in 40 CFR 372.3 as "the preparation of ores to regulate the size (including crushing and grinding) of the product, to remove unwanted constituents, or to improve the quality, purity, or grade of a desired product."

The U.S. Bureau of Mines' Dictionary of Mining, Mineral, and Related Terms (1968) gives much the same definition: dressing or processing ore to regulate the size of the product, remove unwanted constituents, and improve its "quality, purity, or assay grade."

What counts as beneficiation

For its hazardous-waste rules, EPA limits beneficiation of ores and minerals to a specific list of activities (40 CFR 261.4(b)(7)(i)):

• Crushing, grinding, washing, sorting, sizing, and drying
• Dissolution, crystallization, filtration, and precipitation
• Sintering, pelletizing, briquetting, and calcining to remove water or carbon dioxide
• Roasting, autoclaving, or chlorination in preparation for leaching
• Gravity concentration, magnetic separation, electrostatic separation, and flotation
• Ion exchange, solvent extraction, and electrowinning
• Amalgamation
• Heap, dump, vat, tank, and in situ leaching

Smelting and refining are not on the list. The distinction matters: under 40 CFR 261.4(b)(7), solid waste from the extraction and beneficiation of ores and minerals is among the wastes that are not treated as hazardous waste, while only certain listed wastes from later mineral processing receive the same treatment.

Beneficiation under the mining laws

BLM's surface management rules (43 CFR subpart 3809) do not use the word. They cover it within "operations," which 43 CFR 3809.5 defines to include the "development, extraction, and processing of mineral deposits locatable under the mining laws." A mill or processing plant on public land is therefore regulated under the same notice or plan of operations as the mine.

The Mining Law also provides for the land that milling needs. 30 U.S.C. 42 allows nonmineral land "used or occupied ... for mining or milling purposes" to be held as a mill site of up to five acres, and lets the owner of "a quartz mill or reduction works" hold a mill site without owning a mine.

Why it matters in research

Beneficiation leaves tailings, leach pads, and processing ponds behind. On older ground, the remains of a mill are often the most visible sign of past mining. When records are checked for a tract, mill sites, tailings, and the plans of operations that covered them are part of the land's history.